Application of Paris' Law Under Variable Loading

Abstract

The most important characteristics for service safety of welded joints are those describing crack initiation and growth caused by variable loading. Crack initiation and growth caused by variable loading is the subject of numerous investigations. This paper shows the determination of parameters of the fatigue crack for constituents of welded joints produced of high strength low alloyed steel. The crack growth law of Paris establishes the relation between the applied variable load quantity or the corresponding stress intensity factor range and crack growth per cycle. Results have shown that the position of the notch and crack initiation affect the values of the stress intensity range of fatigue threshold Delta Kth and parameters in the Paris' equation.